January 21, 2019

Let’s talk about Invisalign Mandibular Advancement!

This week we have had more publicity about Invisalign Mandibular Advancement. So let’s have a look at it.

As I have said before Invisalign has been a significant development in orthodontic treatment. I am, therefore, very interested in their expansion into the teen market. One innovation that looks interesting is their Mandibular Advancement Appliance.

This is the addition of ramps in the molar region of aligners. These are similar to the blocks in the Twin Block appliance. The amount of mandibular advancement is approximately 2mm per set of aligners, resulting in sequential advancement. At this point, it is relevant to mention that investigators have done several trials on sequential advancement with Twin Blocks and these have shown that there are limited advantages in introducing this step.

A panel of Invisalign providers has tested this appliance, and the FDA has approved it. The definition of this is not too clear, but it means the following:

“The U.S. Food and Drug Administration’s approval process provides consumers with assurance that, once it reaches the market place, a medical device is safe and effective in its intended use”.

Importantly, this does not mean that it “works”.  We need to remember that AcceleDent was FDA approved and look what happened there!


As a result,  we need to be asking questions about its effectiveness. I had a look for case reports, retrospective and cohort studies and I found very little. Although, I understand that there are some case reports on the Invisalign Dr website. However, I found this case report of a patient who had a Class II problem, but this looked like a very mild or even Class I case to me?  In the write up they claim an advancement of the mandible.

Here is a video of the appliance working on a cartoon.

This now brings me to the claims that Invisalign makes in their advertising material. I have looked at the glossy brochure and marketing section of their website. This includes statements by several of their well-paid Key Opinion Leaders.

What are the claims?

These are from the FAQ section of the website.

“Give your patients a better Class II treatment experience. Invisalign treatment with mandibular advancement is a clinically proven, more efficient, more patient-friendly choice.*

  • Save the cost and time of fitting and repairs
  • Treat patients more efficiently
  • Increase patient comfort during treatment
  • Treat patients in late-mixed dentition
  • Correct deep bite in growing Class II patients”.

“This new offering combines the benefits of the most advanced clear aligner system in the world with features for moving the lower jaw forward while simultaneously aligning the teeth. Invisalign treatment with mandibular advancement offers a simpler, more efficient and patient-friendly treatment option than functional appliances to treat teen Class II patients”.

“a multicenter prospective IRB clinical study was completed with 80 patients in North America. Preliminary results from 42 cases thus far show statistically significant correction of Class II malocclusion in growing teen patients”. I have no idea what this means…

What do I think?

I looked closely at the evidence that they quoted on the website about the first claim. The only “proof” that I could find was in the tiny print at the bottom of the page.  They got this data from a survey of 8 of the nine orthodontists who took part in the clinical study.  They asked them questions on chairside time and whether they thought that the appliance was “patient friendly”.

There was no evidence to support the statement that this was better than other Class II correctors.

Furthermore, I would be amazed to find that this appliance causes mandibular growth (moving the lower jaw forwards) as we know that no functional appliance can do this.

I am wondering at what level of evidence the company and the KOLs are working. This is far from convincing.

Final thoughts

In an ideal world, companies or inventors should test their innovations in a clinical trial.  However, there are many cases when this is not possible or necessary. For example, when Bill Clark invented the Twin Block, the initial evidence level was case reports. It was trialled several years later after many operators adopted it as a method of treatment.

There was nothing wrong with this approach because extreme claims were not made for its effectiveness and it was freely available as part of the orthodontic armamentarium. Bill Clarke did not charge a fee for every Twin Block that was made.

However, this is different. They are claiming that the new Invisalign appliance is better than other Class II correctors. They are also suggesting that it grows jaws. This is what I have a problem with. These claims are potentially misleading and are similar to those made for other recent developments in orthodontics.  Perhaps this is a sign of the times, but there should be a time when we say no, we do not believe you. I wonder if this is long overdue.




Related Posts

Have your say!

  1. I believe it would be much more prudent not to speak of mandibular growth but rather a mandibular repositioning as part of Class II camouflage.

    • I would rephrase it as mandibular DENTOALVEOLAR repositioning as there is no evidence that the appliance actually repositions the mandible.

  2. Is it time for KOLs to have to pass a formal qualification before they can call themselves this ???
    No one in the profession is sure what it means or how one becomes a KOL.
    A pseudo ~ qualification granted by a dental company means little and is ,frankly ,self serving.
    We are willing to listen to anyone’s opinions with as much factual backing as possible .You don’t have to try to add authority by “KOL”.

  3. Dear Dr. O’Brien

    I have been reading and enjoying your blog for several years. I have noted that in the article in Invisalign it is mention that they have FDA “approval” for their recent modification. However, that would require going through a PMA process with the FDA. Perhaps they did it via a PMN process where they do not have to submit significant clinical trials. Would you mind clarifying this?

    Thank you.

  4. Just a few clarifications if I may:
    You say Kevin that, These are similar to the blocks in the Twin Block appliance.” but they are actually more like a MARA because the blocks engage on the buccal, not the occlusal.
    Perhaps what they mean when, “They are claiming that the new Invisalign appliance is better than other Class II correctors.” is that simultaneously with holding the mandible in protrusion, the aligners continue to open the bite and straighten teeth and in that sense, they may be more efficient. Full disclosure: I partook in the clinical trial.

  5. Hi Kevin:
    Do you mean Bill Clark? If so, I did/published some of his data and noted there are (unwanted) midfacial side-effects when the mandible is protruded using these types of devices. Also, I would be concerned if the mandible didn’t grow in these actively-growing kids.

    Singh GD and Hodge MR. Bimaxillary morphometry in patients with Class II division 1 malocclusion treated with Twin Block appliances. Angle Orthod. 72(5), 402–409, 2002.
    Singh GD and Clark WJ. Localization of mandibular changes in patients with Class II division 1 malocclusions treated using Twin Block appliances: finite-element modeling. Am J Orthod Dentofacial Orthop. 119(4), 419-425, 2001.

  6. Kevin, I really appreciate your questioning of these growth claims with basically a modified delivery of the Twin Block appliance. Having been practicing Orthodontics for 31 years, I have seen and heard endless claims about this or that company or person having the secret sauce to treat various problems, but the final analysis of these treatments most times requires years to prove/disprove.

    Unfortunately, by the time the research concludes the lack of effectiveness of these treatments or appliances, the “inventor” has made the financial windfall and drifts into oblivion. In some cases the treatment philosophy lives on because nobody objects to the lack of validity or effectiveness.

    A well known company originally claimed their self ligating bracket allowed one to treat more cases non extraction because the difference in physiology related to the light forces. This has always amused me because this bracket and force system is very similar to the old Begg system that was used many years ago. In one of the original lectures for this bracket a Canadian engineer was hired to create this complex machine that mimicked an occlusion to demonstrate the delivery of light forces that the body then transformed into “physiological expansion.”

    This is just one example of a company and/or inventor making claims and getting enough so called “experts” to tout it until the claims were believed by enough to gain traction. Although years of dedicated scientific research has rejected most of the claims made by these “new treatments “ our specialty still uses and swears by these unfounded and unproven methods of moving teeth. This new mandibular advancement appliance is just another widget that a company claims is revolutionary and advertises until many in our profession adopt because they hate to feel like they are not on the “cutting edge.”

    In the end, the profession of Orthodontics is not being helped by these unscientific claims and devices. We are being led not by science, but by marketing departments and hired “experts” who amazingly shift every year or so to be an expert for a different company or philosophy. I just wonder if the check in the mail leads them to believe in this new way of moving teeth and growing mandibles. Meanwhile, I still move teeth with braces and some aligners and sleep very well at night knowing I have tried to treat every patient with science and biology as my guide.

  7. There is nothing wrong with KOLs per se. There is everything wrong with KOLs who delude their audiences with unacknowledged selection bias, confirmation bias, kludging the evidence, not presenting evidence, ignoring failures and dropouts, cost-benefit analysis – ie those who use all the tricks instead of taking the honour of speaking to an audience seriously enough to present science, honesty. Companies all too often rely on the fact that “a lie gets halfway round the world while truth is getting its boots on.” Then they just move on to something new, all the while liberally employing gish galloping and Occam’s Hairdryer with no remorse except for their share price. Whatever the truth is about the MA appliance you can be certain it is not what you are being told by the company – breakages, need to employ elastics with the appliance, underwhelming case examples, costs

  8. Does this lack of evidence in advertising claims leave Align open to possible legal action in the U K of elsewhere?

  9. It almost looks like Invisalign are going a bit retro with the growing mandibles bit since we now apparently believe that that functionals don’t do this. On the other hand the AJODO is still called the AJODO even though the term dentofacial orthopedics is probably meaningless.

  10. In fairness, if Bill Clark was reponsible for making every Twin Block on earth, he’d be in his rights to charge a fee.

    Is it better? Well if it works then it probably has a few advantages over other functionals, not least that it does the aligning at the same time. Browns, seasons, thickens.

    So it comes down to “does it work?” Obviously it’s a bit silly if they make daft claims for it, I’d prefer if they just claimed it corrected class II buccal segments, or distalised upper buccal teeth. And then actually DID THAT. So that’s what the big number clinical trials will tell us when they come out.

    They’re coming out, right?

    And then as a bonus, I don’t want my lower incisors to procline. I almost never seem to have retroclined upper incisors, which some manufacturers present as a big bogeyman, but those lower incisors? Won’t stay put. So yeah, Aligntech, if you can fix that too I’d be happy.

    Swords Orthodontics

  11. At one time, the AAO held its members accountable when they made claims of superiority over other practitioners. Can we do the same with these third party companies that are now treating patients in their aligner stores all the while claiming superiority over those of us who still function in the realm of science and biology? If they are making claims that their widget is superior to ours, can we effect them in a negative way?

    Is there a doctor treating the patients in these aligner stores? If yes, then we should be able to hold them accountable for their claims of superiority. If not, then these companies are practicing dentistry without a license, right? Either way, their claims of superiority are going unregulated by our profession.

  12. Hi Kevin, thanks for your blog and useful information.
    So compared to aligners, do MARA or Herbst appliance actually cause mandibular growth? For they also good for mandibular dentoalveolar repositioning?

    I am a physician not a dentist, but very interested in this topic as my daughter has type II malocclusion and is being treated with aligners, and I am very apprehensive now knowing that aligners may not be the best treatment option for her. I tried to find any article providing some conclusive evidence, but failed.

    Many thanks to you and all the other dentists who are responding here.


    • HI and thanks for the comment. There has been a large amount of research into the “growth modifying” effects of functional appliances. These include the Herbst, although there has not been much on the MARA. This research has shown that no orthodontic appliance can increase mandibular growth. The profile changes that we see are likely to be due to the repositioning of the teeth. Whether aligners are the best method of treating Class II problems in comparison to other well established and effective methods is unknown as there has been no research done on their use for these problems. I hope that this answers your question and I am sorry about the delay, I have been on holiday. Best wishes: Kevin

  13. Thank you all for the comments. My 12 year old daughter is getting her first round of orthodontic treatment (Invisalign) at this time, and we are having a tense discussion at home between myself and my spouse about what is possible and what can be expected with regards to mandibular advancement. In particular, my spouse expects that Invisalign can “correct the deep bite and move the jaw forwards, so that the chin will be more prominent”. Supposedly this is now standard in China and Taiwan, and supposedly there are plenty of YouTube videos that document the mandibular advancement that can be obtained with Invisalign.

    I however believe that we shouldn’t expect too much in regards to mandibular advancement (not to mention that the issue is minor, and I think it is uncalled for to scrutinize your own child more severely than the trained orthodontist would).

    In short, my spouse essentially demanded that the orthodontist should focus on mandibular advancement, and deliver solid results in that regard. I think that’s unfair to both the orthodontist and to the child. We’re just using aligners here, not surgery.

    So what is the consensus? Is mandibular advancement, so that it results in an easily noticeable improvement in the chin position, even possible with Invisalign? And whatever advancement is possible, wouldn’t the orthodontist already include that in the Invisalign treatment plan, without needing to be reminded by an overzealous parent?

    In my opinion, my spouse is basically begging for a chance to pay extra in return for unrealistic promises. I’m glad the orthodontist pretty much went the other way and said my spouse shouldn’t expect anything beyond straight teeth. That’s the honest take on things, right?

Leave a Reply

Your email address will not be published. Required fields are marked *